🐛 build-labels cannot be multiline

[azz]

The handling of multi-line strings for build-labels is incorrect.

Input:

# BUILDKITE_MESSAGE="foo\nbar"

build-labels:
    - "commit.message=${BUILDKITE_MESSAGE}"

Expected:

$ docker inspect my-image  | jq .[0].Config.Labels
{
  "commit.message": "foo\nbar"
}

Actual:

{
  "commit.message": "foo",
  "bar": ""
}

This is probably due to the read here:

docker-compose-buildkite-plugin/commands/build.sh

Lines 71 to 74 in 4ac4d6d

	labels=()
	while read -r label ; do
	[[ -n "${label:-}" ]] && labels+=("${label}")
	done <<< "$(plugin_read_list BUILD_LABELS)"

[azz]

Tangentially related, would be nice if you could provide a map/object instead of an array of labels. It makes merging them with YAML easier.

[toote]

@azz this is really a head-scratcher 🤔 Unfortunately, due to the limitations of having to use bash to process all this information I could not find a way to resolve this issue but we'll keep thinking about it!

For the time being the best we can do is add a warning that multi-line values in the labels will result in unexpected behaviours :(

If you have any suggestions it will be more than welcome.

if you could provide a map/object instead of an array of labels

I thought this was a neat idea until I realized it has a fatal flaw. Object keys are used to create a bash-compatible variable name with the value associated to the key and there would be no way to reconstruct the original key as every non alphanumeric character will be replaced with an underscore and everything will be uppercase. For example (the array is just to exemplify, removing it wouldn't make much of a difference), if the plugin's configuration had something like build-labels: [ 'commit.message/Very_Important' : 'extremely importat value' ] it would get translated by the agent to the following environment variable: BUILDKITE_PLUGIN_DOCKER_COMPOSE_BUILD_LABELS_0_COMMIT_MESSAGE_VERY_IMPORTANT="extremely important value" 😢

[azz]

ah that's unfortunate! sounds like a limitation of the parameter serialisation format. is there any way to have the config in a single env var encoded as JSON, e.g:

BUILDKITE_PLUGIN_DOCKER_COMPOSE # with the value as JSON

instead of?

BUILDKITE_PLUGIN_DOCKER_COMPOSE_BUILD_LABELS_0_COMMIT_MESSAGE_VERY_IMPORTANT

[toote]

That is actually handled by the agent's code and is not configurable